1. Field of the Invention
This invention relates to a recording and/or reproducing apparatus in general, and more particularly to a device for automatically opening and closing the shutter of a magneto optical disc cartridge used with magneto optical recording and/or reproducing apparatus. The shutter is opened when the cartridge is inserted, and closed when it is removed.
2. Description of the Prior Art
A magnetic or magneto optical disc has recently been introduced as a medium for magnetic or magneto optical recording.
In the U.S. Pat. No. 4,517,617 issued to Ohkawara discloses a disc cartridge comprising a hard jacket made from such material as plastic. The recording disc is substantially enveloped within the hard jacket for preventing damage and contamination of the disc itself and/or a recording area thereof which otherwise might occur when handling the disc or inserting it into the recording and/or reproducing apparatus. The hard jacket is provided with an aperture for insertion of a magnetic head mounted on the recording and/or reproducing apparatus when installed or loaded thereon. This head insertion aperture is normally closed by a shutter member slidably connected to the hard jacket, capable of preventing dust or fingerprints from entering through the head insertion aperture, and therefore preventing contamination of the recording area of the disc. The shutter is provided with an access window which will allow the magnetic head to obtain access to the recording area of the disc, when the disc cartridge is loaded into the apparatus, for performing a desired recording and/or reproducing operation.
With the system and apparatus disclosed in the above-referred U.S. Pat. No. 4,517,617, the shutter must be hand-manipulated to be laterally slid or opened before the disc cartridge has been loaded into the apparatus, and manually closed after completing the desired recording and/or reproducing operation. Further, the operator's fingerprints or other foreign matter would tend to be adhered to the recording area of the disc when manipulating the disc cartridge for opening or closing the shutter.
Such problem can be solved by a mechanism or device capable of automatically opening and closing the shutter as the disc cartridge is being inserted into the apparatus and discharged out of the apparatus. An example of such shutter actuating devices is disclosed in the Japanese Utility-Model Publication No. (Sho) 62-15895, which includes, as diagrammatically shown in FIG. 12, an operating lever D rotatably mounted on a cartridge holder A of the recording and/or reproducing apparatus and a cut-out notch G formed at the front edge of the shutter C. The lever D has at its one end a vertical pivot E located on the inserting side, connected to the holder A, and at the other end an engaging pin F located at the other side, adapted for engagement with the notch G of the shutter C. During insertion or advancement of the cartridge B into the holder A, engagement between the engaging pin F and the notch G will cause the lever D to rotate in the counter clockwise direction, so that the shutter C is laterally slid within a recessed section I of the cartridge B, against a biasing force of a spring (not shown). Thus, the shutter C may be completely opened. When the cartridge B is being ejected from the loaded position in the apparatus, the lever D is rotated in the opposite direction due to a spring H connected between the holder A and the lever D, so that the shutter C will be automatically closed.
With this prior art arrangement, the lever D will be in contact with the front edge of the cartridge B (the shutter C) at an acute angle during the initial stage of insertion of the disc cartridge B, so that the lever D may be smoothly rotated with a slight pushing force applied to the cartridge B. However, as the cartridge B is further advanced into the holder A, an angle between the lever D and the front edge of the cartridge B becomes closer to a right angle, which would prevent smooth rotation of the lever D. Accordingly, a considerable force will be required to actuate the shutter C as the cartridge B approaches the fully loaded position.
In the above-referred prior art device, the lever D is arranged substantially above the shutter C of the disc cartridge B when it is fully loaded in the holder A of the magnetic recording and/or reproducing apparatus. This requires a considerable space or area for arrangement of the shutter actuating mechanism above the apparatus.
In another type recording and/or reproducing apparatus for use in combination with a magneto optical disc, it is necessary to mount a bias magnet on the apparatus opposite an optical head mechanism, across the magneto optical disc in the full-loaded cartridge. In this arrangement it becomes difficult or practically impossible to install the shutter operating lever substantially above the shutter as in the above-referred prior art device.
It has been attempted to modify the above-referred prior art arrangement of the shutter operating lever D such that the pivot E is mounted relatively in the backside of the apparatus, with the engaging pin F located at the inserting side. Such modification can leave a substantial space above the shutter C available for arrangement of the bias magnet. However, in order that the shutter actuating device shown in FIG. 13 may operate smoothly, it is necessary that the lever D should always be inclined with respect to the cartridge inserting direction. More specifically, even when the disc cartridge B is still in the unloaded position, the pivot E should be positioned outward (or rightward in the drawing) of the engaging pin F. This requirement cannot be satisfied in the case of the magneto optical recording and/or reproducing apparatus because of a limited space between the engaging edge of the shutter of the magneto optical disc cartridge and the side face of the cartridge, which is not enough to arrange the shutter operating lever D in the manner as shown in FIG. 13.
Standardization of a specific format of the magneto optical disc cartridge is now being settled. In accordance with the format, such disc cartridge construction as shown in FIG. 3 has been proposed. A shutter 50 is slidable within a recessed portion 45 of the disc cartridge 44. The shutter 50 has no cut-out notch G and may be actuated through engagement between an engaging edge 50 of the shutter 50 and an engaging portion of a shutter actuating device. The engaging edge 50 in the shutter closed position is positioned in close vicinity to the side face of the disc cartridge 44.